1. Field of the Invention
The present invention relates to an image forming apparatus and control method therefore which has a master CPU and a slave CPU to control an image forming operation by communication between these CPUs.
2. Description of the Related Art
In conventional printer apparatuses, a master CPU and ASIC (dedicated customer LSI) are arranged on a main circuit hoard to cause the ASIC to control all loads such as a pulse motor driving module and high-voltage module. In an energy saving mode for saving power consumption while the printer apparatus is left unused for a predetermined period of time, the ASIC also controls to, for example, decrease the clock frequency and driving supply voltage to the master CPU or set them to zero.
Japanese Patent Laid-Open No. 10-031531 is available as a reference which discloses the above technique. This reference describes a technique for reducing power consumption by decreasing the clock frequency and supply voltage to the (master) CPU under a predetermined condition such as standby. Japanese Patent Laid-Open No. 2002-086844 describes a printer apparatus which prints while a clock signal and driving current are reduced, in non-urgent time designation printing (timer printing) in the time zone during which the frequency of usage of the printer apparatus is low.
The above-described prior arts decrease the clock frequency and supply voltage to the master CPU or set them to zero to do control while suppressing power consumption. This equally sets all the loads in the printer apparatus to an energy saving mode. In this manner, the conventional techniques cannot set optimal energy saving modes separately for a plurality of loads and can hardly attain further suppression of power consumption.